The extreme rainfall over eastern Australia, culminating in the devastating floods in Queensland over the past few weeks has given rise, again, to much talk about climate change. It was the subject of an email discussion within our local nascent Transition Towns group last week, with one member suggesting that we should avoid making links between the floods and climate change as this is ‘airy fairy’ and plays into the hands of the climate change sceptics and deniers and that we should stick to the ‘science’ of climate change if we are to make any difference.
He then went on to discuss various oral histories and records of how the Federation drought had been so much worse than the most recent one, and how the 1893 Brisbane flood eclipsed this one, and how, according to an interview given by his great-great aunt in 1900, people were dropping dead from heat in the streets of Adelaide in the 1850s – a heat much worse, apparently, than the heat waves they get in Adelaide now. His point being that our weather is cyclical and the current extreme events, including the floods, are simply part of that cycle.
Well, he’s half right – our weather is cyclical and in Australia, droughts are typically broken by floods. But he’s wrong if he thinks that avoiding comparisons is going to make any difference to the rump of sceptics who want to dismiss anthropogenic climate change as a myth – the climate change deniers are already using precisely those comparisons to prove their own point.
Yes, we should avoid comparing current extreme weather with similar events in history, but for another reason: such comparisons are irrelevant.
The Adelaide of the 1850s, to take one example, was a much different place to its modern version. Many more people would have been recent immigrants from Europe, completely unprepared for the searing South Australian summer. They would also have been dressed completely inappropriately for the heat – women would have worn long dresses with petticoats, men in jackets. There were no board shorts and thongs, t-shirts and sarongs. There were also no air conditioned shopping malls or cinemas in which to escape the heat, in fact, no airconditioning at all, no swimming pools and no refrigeration. To suggest that the heat in South Australia in the 1850s was worse than it is now on the basis of oral histories, and therefore draw the conclusion that we can’t attribute single events to climate change, is to try to make our current world fit neatly into that of the 1850s with no bits left hanging outside the lines. It simply does not work.
Likewise, comparisons between the Brisbane flood of 2011 and previous disastrous floods are fallacious. The climate change deniers are already using the 1893 as their ‘proof’ of the non-existence of climate change. How do “… scientists explain that the worst floods in Brisbane’s history occurred in 1893?” they shriek self-righteously on their website, Climate Change Denier (which interestingly, bears a logo very similar to that of BP – I’ll follow up on that and find out if there’s a link). Of course they have rainfall statistics to back up their argument, which is, essentially, the flood in 1893 was bigger, there was more rainfall, and thus there is no climate change.
The flood of 1893 engulfed much of the Brisbane CBD – pictured is Queen St. However, there was no flood mitigation in the form of Wivenhoe Dam and the river itself was different – navigable for further upstream and less affected and altered by urbanisation. Effectively, there was less to stop or hinder the progression of floodwaters making their way to Moreton Bay via the most direct route – the Brisbane River. To suggest that a single event (the 2011 flood) cannot be indicative of climate change on the basis of another single event (the 1893 flood) is a meaningless argument.
Comparisons with 1974 are also wide of the mark. The current flood is the result of sustained, heavy rainfall over an extended period. The 1974 event was the result of sudden, torrential rainfall in the wake of a cyclone. Quoting rainfall statistics, as the climate change deniers are fond of doing, is completely irrelevant without the context.
Climate change is measured by trends, not single events. Single events, however, can be directly caused by or indirectly influenced by trends. Climate scientists have not suggested that the flood is direct evidence of climate change, but rather the other way around: ANU’s Professor Will Steffen, who is one the Prime Minister’s advisors on climate change, said, “As the climate warms, there is more water vapour in the atmosphere. This means that there is a probability that there will more intense rainfall events around the world. There is some evidence that we can see them now. I think the place where the best data is the US.” University of Melbourne’s Professor David Karoly echoed this: “…the wild extremes being experienced by the continent were in keeping with scientists’ forecasts of more flooding associated with increased heavy rain and more droughts as a result of high temperatures and more evaporation”.
Sticking to the ‘science’ of climate change is important, but it is just as important not to play into the simplistic arguments of the sceptics by falling into the very traps that they use – focusing on single events as ‘proof’. We know now that 2010 equals 2005 as the hottest years on record. We know that the 11 hottest years on record have occurred in the last 13 years. These are the trends on which the science is based. Far from being ‘airy fairy’ though, the single events are indicative of the results of these trends and must be taken into account when considering climate change – just not as comparisons.
Pictured below is the historic Breakfast Creek Hotel in Brisbane in the 1893 (left) and 1974 floods. I don’t know how it fared this time around.
More info on climate change and the floods from the Climate Action Centre.